This invention relates generally to a method and apparatus for establishing an attachment connection between a dental prosthesis body such as a dental bridge and an anchoring tooth or crown, and more specifically to a construction of a precision attachment connection which is relatively simple to produce, and effective in its use.
In dentistry, attachments have a great importance, in particular, in the case of a partial plate or bridge or any other removable dental prosthesis. In these cases, the female die of the attachment mechanically joins, via the male die of the attachment, a prosthesis body with a crown or with an anchoring tooth. Attachment fittings of the prior art are essentially a concentric double anchoring system. They consist of a fitting part, namely a female die with a hollow or negative form, and a male die as a positive form. In general, the female die is provided on a crown or on an anchoring tooth, while the male die is anchored to the prosthesis part. There are principally two basic types of connections between a dental prosthesis body and an anchoring tooth. In one type, a male die is cast on the dental prosthesis body. In this arrangement, however, numerous problems occur principally due to the difficulty in accuracy in the dimensions of the parts comprising the entire arrangement. Unless accurately formed, the attachment can be fitted together only with difficulty and the parts of the attachment can be separated from one another only with difficulty.
The second type of connection involves producing, on a crown and/or on an anchoring tooth, a corresponding recess for acceptance of a female die body. The female die body, in this case, is welded into this anchoring tooth. Then, likewise welded on the prosthesis part that is to be joined with the anchoring tooth is a housing for attachment of a male die body. Additionally, the male die body is provided with an anchoring part that can be fitted into the housing in question and locked in place. Here, the housing is welded to a so-called skeleton prosthesis, and an appropriate flesh-colored plastic, protective coating is placed over this skeleton prosthesis and the housing.
When anchoring a dental prosthesis, for example a replacement for the lower back teeth, to a front dental crown, four extremely expensive welding procedures are needed for joining the corresponding female die and housing bodies which are used to accept the male die. These welding steps are often found to introduce alignment problems. Since the corresponding welding of the housing parts and of the female die body must be done with adequate precision in order to be able to introduce the male die into the female die body easily and without canting, this procedure has not been too satisfactory.
Moreover, there is always a further disadvantage, in particular when using the so-called "burn-on" technique. The use of this technique, in particular for front tooth parts, involves burning onto a noble metal alloy, at high temperatures (over 1000.degree. C.) tooth front parts consisting of natural tooth-like ceramic. It is found that when burning on the ceramic at such temperatures, the corresponding weld spots run out. As such, there is the danger that the corresponding female die bodies will break off with strong stresses.
Dental casting techniques are also known with respect to the mounting of an attachment part on a skeleton prosthesis. Here, a housing for the anchoring part of a male die is formed which is capable of being firmly screwed on. This process affords the advantage that the male die, which may consist of V2H steel, is interchangeable. Accordingly, firm screwing down of the housing to an attachment part requires an additional work step wherein a firm and stable connection becomes possible only in a limited number of cases.